A reciprocating piston type compressor having a cylinder block, a plurality of cylinder bores, and at least a housing closing an end of the cylinder block. The housing contains a suction chamber for a refrigerant gas to be compressed and a discharge chamber for the compressed refrigerant gas discharged from the cylinder bores in response to reciprocation of a plurality of pistons. The compressed gas is discharged through discharge ports closed by a discharge valve element having a plurality of integral discharge reed-valves movable between a closed positions and a predetermined open positions. The open position is defined by a stop unit integrally formed in an inner wall of the housing. The stop unit has a plurality of flat stop faces formed on the inner wall to permit free ends of the discharge reed-valves to come into contact engagement therewith, when the discharge reed-valves are moved from the closed positions to the open positions.